Homicide charges were dropped Tuesday by the San Francisco District Attorney’s Office against a teenage boy who had been accused of fatally stabbing a 14-year-old boy in the city’s Mission District last September.

The Homeland Security Department’s border drones program costs far more than the government estimates, helps in the arrests of just a fraction of the number of people trying to cross the border illegally and flies far fewer hours than the government claims, an internal watchdog asserted in a report released Tuesday.